Consumer weblog "Which?" tested the most popular 7- and 10-inch tablets to compare battery life, and found quite a bit of variation. If you're looking for a new tablet, here are some things to watch out for.

You can never really tell how an advertised battery life relates to real-world battery life, so "Which?" is here to help. Unsurprisingly, the iPad and the iPad Mini took first place in the 10-inch and 7-inch tests, respectively, but even if you aren't an iPad fan, there's a lot to glean about Android and Microsoft. For example, the 10-inch Samsung Galaxy Tab does a bit better than the Nexus 10, and a lot better than the Asus Transformer Prime (at least without they keyboard, since the keyboard contains an extra battery). At the same time, though, the Kindle Fire HD and Nexus 7 seem to do significantly better than the 7-inch Galaxy.

Obviously battery life isn't everything, but it is something to keep in mind, whether you're buying for yourself or as a gift for someone else. Hit the link for more info on how the tests were run and for other details.